AP Chemistry - Chemical Equilibria

A series of flashcards covering key concepts related to chemical equilibria, including definitions, principles, and relevant equations.

Chemical Equilibrium

The state where the concentrations of all reactants and products remain constant over time.

Equilibrium Constant (K)

A ratio of the concentrations of products to reactants raised to the power of their coefficients in the balanced equation.

Reaction Quotient (Q)

A value that indicates the direction in which a reaction mixture will shift to reach equilibrium.

Le Châtelier's Principle

States that if an external change is applied to a system at equilibrium, the system will adjust to counteract that change.

Kp

The equilibrium constant for gases in terms of partial pressures.

Kc

The equilibrium constant for reactions in terms of concentrations.

Law of Mass Action

The proposition that the ratio of the concentrations of products to reactants is constant at equilibrium.

Hess's Law

A principle stating that the total enthalpy change in a reaction is the sum of all changes.

Dynamics of Equilibrium

The concept that equilibrium is dynamic, with both forward and reverse reactions occurring simultaneously.

Homogeneous Equilibrium

Equilibrium that involves reactants and products in the same phase.

Heterogeneous Equilibrium

Equilibrium involving substances in different phases, where only those in the gaseous or aqueous states are included in the equilibrium expression.

Solids and Pure Liquids

Do not appear in equilibrium expressions because their concentrations remain constant.

Temperature Effect on Equilibrium

Changes in temperature can change the value of the equilibrium constant.

Chemical Equilibrium

The state where the concentrations of all reactants and products remain constant over time.

Equilibrium Constant (K)

A ratio of the concentrations of products to reactants raised to the power of their coefficients in the balanced equation.

Reaction Quotient (Q)

A value that indicates the direction in which a reaction mixture will shift to reach equilibrium.

Le Châtelier's Principle

States that if an external change is applied to a system at equilibrium, the system will adjust to counteract that change.

ICE Table

A tool used to organize the initial concentrations, changes, and equilibrium concentrations of reactants and products.

Kp

The equilibrium constant for gases in terms of partial pressures.

Kc

The equilibrium constant for reactions in terms of concentrations.

Law of Mass Action

The proposition that the ratio of the concentrations of products to reactants is constant at equilibrium.

Hess's Law

A principle stating that the total enthalpy change in a reaction is the sum of all changes.

Dynamics of Equilibrium

The concept that equilibrium is dynamic, with both forward and reverse reactions occurring simultaneously.

Homogeneous Equilibrium

Equilibrium that involves reactants and products in the same phase.

Heterogeneous Equilibrium

Equilibrium involving substances in different phases, where only those in the gaseous or aqueous states are included in the equilibrium expression.

Solids and Pure Liquids

Do not appear in equilibrium expressions because their concentrations remain constant.

Temperature Effect on Equilibrium

Changes in temperature can change the value of the equilibrium constant.

Relationship between Kp and Kc

The mathematical relationship is expressed as Kp = Kc(RT)^{\Delta n}, where \Delta n is the moles of gaseous products minus the moles of gaseous reactants.

Effect of a Catalyst

A catalyst increases the rate at which equilibrium is achieved but does not change the position of equilibrium or the value of the equilibrium constant.

Effect of Pressure on Equilibrium

Increasing pressure (by decreasing volume) shifts the equilibrium toward the side with fewer moles of gas.

Magnitude of K

If K \gg 1, the equilibrium favors the formation of products; if K \ll 1, the equilibrium favors the reactants.